Vehicle actuated traffic signal



Aug. 27, 1940. P. P. HORN] 2,212,986

I VEHICLE ACTUATED TRAFFIC SIGNAL Filed Dec. 2, 1937 5 Sheets-Sheet l Fig. 2

INVENTOR PAUL P. HORNI Aug. 27, 1940. HORN] 2,212,986

VEHICLE ACTUATED TRAFFIC SIGNAL Filed Dec. 2, 1937 3 Sheets-Sheet 2 INVENTOR.

PAUL P. HORN] Aug. 27, 1940. P, RN, 2,212,986

VEHICLE ACTUATED TRAFFIC SIGNAL Filed Dec. 2, 1937 5 SheetsSheet 3 2 22 r0 VEHICLE CONTROLLED I APPARATUS 40 I l 23 1 I L J Pi g 5 ELECTRO SENSITIVE ELEMENT TO VEHICLE CONTROLLED APPARATUS ELECTRO SENSITIVE ELEMENT PAUL? HQR atented Aug. 27,

This invention relates to signaling systems, and more particularly to the type which utilizes a device located in the street for the detection of a vehicle passing within a certain variable range.

It is common practice in signaling systems, particularly those systems relating to the control of trafiic of a vehicular type, namely, automobiles and the like, to employ what is commonly referred to as detectors. The detectors are generally classified as either mechanical or magnetic. In the mechanical type of detector, the vehicle must actually engage a contactor which is located in the street, in the path of the vehicle. As the vehicle engages the contactor, an electrical circuit is completed, which causes certain apparatus to function, which, through a series of operations, eventually causes a trafiic signal to be operated. In the magnetic type of detector, a device is placed in the street in the vicinity of the path of the vehicle to be detected, said detector being actuated by the passage thereover or thereabouts, due to the presence of a mass of magnetizable material, the vehicle, per se, not physically engaging or pressing any tangible element. While it is old in the art to use a coil with a simple core as a magnetic detector, this is, perhaps, one of the simplest forms of magnetic detector.

Heretofore, it has always been a great problem in traffic signaling using magnetic detectors to obtain a system wherein the trafiic light would not be operated by flux change caused by line surges, due to fluctuating loads traveling through detectors in the vicinity of the magnetic vehicle detectors. Further, one of the problems of traffic control has been to properly operate signaling apparatus where it was necessary-to control said apparatus by a vehicle traveling at one level, and not have the signal operated by a vehicle passing within range of the detector, but at another level.

It is further pointed out that while there have been magnetic detectors which were usable to give certain results for the control of signaling apparatus, there are many cases where the vehicle itself 'carried a permanent magnet for the purpose of generating a current in a sensitive instrument, due to the cutting of the magnetic field by conductors of the coil of said magnetic detector. To provide a detector which requires this type of permanent magnet installation on a vehicle, is definitely costly in itself, and further undesirable, due to the, installation charges.

A great deal of experimentation and scientific research has disclosed that all vehicles are fundamentally and inherently magnetized. This may be due to many causes, such as the aligning of the parts of the metal used in construction to form resultant magnetic poles, or partly due to the formation of a number of independent magnets. It is well known that a ship will take on a given polarity, due to the position in which it rests when actual construction has taken place. From many causes a vehicle, therefore, is a huge magnet, or a multiplicity of several magnets. Tests indicate that a front and rear bumper of an automobile may each be independent magnets and that the vehicle itself will have many opposing polarities, which may be manifested by moving a compass in the vicinity of various parts of the vehicle. Regardless of the peculiar polarities of various vehicles, it is nevertheless established by tests that the vehicle in itself does possess enough magnetic material to produce magnetizing lines of force emanating therefrom to cause a current to flow or'a voltage to be set up in a detector of the type herein employed.

It is, therefore, an object of this invention to utilize masses of material being inherently magnetized, such as automobiles, to cause the operation and control of traffic signaling systems.

Anther object is to provide an operating circuit for traflic control apparatus, which circuit will not respond to slight variations of flux density due to power line surges, caused by sudden increases or decreases in the power load, such as might be caused by starting or stopping a surface or subway car, assuming the power conductors to be located adjacent or in the immediate vicinity of the detectors in said operating circuit.

1 A further object of the present invention is to provide a system employing a plurality of detectors, the arrangements of which are such that signal actuation will occur, due to the passage of the vehicle within a certain range of the detector, irrespective of the precisepositioning of the vehicle in relation to the magnetic vehicle detecting devices.

A further object is to provide a vehicle detector having a highly permeable core, connected in a normally closed substantially de-energized operating circuit.

A further object is to provide a plurality of detectors having highly permeable cores, said detectors being arranged such that the cutting of the conductors of said detectors by flux may, under certain conditions, such as an equally distributed flux over the several detectors, fail to cause the undesirable operation of the trafiic signals.

A further object of the invention is to provide detectors having cores of highly permeable material, said detectors being so disposed that the effective range of a vehicle from said detectors may be controlled.

A still further object of the invention is to provide magnetic detectors of the type described, arranged so that a vehicle passing said detectors at one level will cause the operation thereof, while a vehicle passing at a different level, for instance, by using an underpass, say at substantially ninety degrees from the direction of travel of said first mentioned vehicle, will not cause operation of the traffc signal.

In view of the foregoing statements and ob,- jccts, I will now describe the principle of operation of this invention in connection with certain of the apparatus which I feel is'illustrative of one arrangement thereof, but it is to be understood that the following disclosure is merely illustrative and that the invention may be modified in conformity with the claims of the material presented herewith.

Referring now to the drawings:

Fig. 1 is a perspective view, partly shown in section, of an elevated highway and an underpass therefor, showing the location of power lines in relation to certain of the detectors, and also showing the location of the trai'lic lights and controller.

Fig. 2 is a plan view of certain street intersections showing the traffic controller, and detectors, certain of said detectors shown in relation to power lines, and a potential conflicting lane for flow of traific in relation to operation of the detectors.

Fig. 3 is a sectional view of Fig. 1, looking to the left thereof, said cut being taken just ahead of the vehicle shown on the elevated highway, the car underneath the detectors being positionally changed to show a definite condition for purposes of explanation.

Fig. 4 is a schematic view, more clearly showing a coil of wire wrapped around a core.

Fig. 5 is a schematic representation of an operating circuit connecting several detectors with the input of an electro-sensitive element used to operate certain control apparatus.

. Fig. 6 is a view showing an electro-sensitive element, of the tube type, which may be used for connection with vehicle control apparatus.

Fig. 7 is an elevation symbolically showing a vehicle approaching two magnetic detectors.

Referring particularly to Fig. 1, we have an elevated highway I, crossing at right angles to the flow of traffic on an underpass 2, the trafiic on the elevated highway being controllable by trafiic signal lights 3 in response to the operation of the apparatus and the controller 4, caused by actuation of the detectors 5 and 6,. The arrows I, 8 and 9 indicate the general direction in which the individual traffic signal groups pointso that they may control the traffic coming from that particular direction. The power lines, which may be considered as a group 9, are shown to be suspended above the detectors 5-6, and are at substantially right angles to the longitudinal axis of either of said detectors.

In Fig. 2 we see the controller 4, which operates the traffic light 3 in response to detectors 5 and 6, being an arrangement similar to that view shown in Fig. 1, with the exception that the detector I0 is placed at an intersection one city block in distance from the intersection shown to the right of Fig. 1. The purpose of this view, Fig. 2, is to indicate that the detector H), which will later be described in connection with Fig. 5, is electrically connected to the operating detector circuit to control the traffic light 3 through the controller 4. The detector I0 is shown to be an independent detector for simple operation by a vehicle, the operation of which would be fundamentally the same for any of the detectors electrically wired to be used separately for the detection of vehicles passing within the proper range.

Figs. 1 and 2 give a birds-eye view of the problem at hand, and while the detectors 5 and 6 are shown dotted, it is to be understood that they may be embedded in the concrete or may even be placed below the road bed of the elevated highway I, so that they may be observed by inspection from a position on the underpass located under the elevated highway I.

This may be shown somewhat more in detail by noting Fig. 3, wherein the detectors 5 and 6 are represented as having cores l l-l l' and being encased in a tubing l2-|2', respectively, which may be of fibre or metal, such as brass. A concrete highway I3 is shown as being representative of the elevated highway I of Fig. 1, on which the vehicle I4 is shown in a position in close proximity to said detectors 5 and 6. The vehicle l5 on the lower part of Fig. 3 is shown as having the lines of force "5 emanating therefrom and expanding outwardly so that they actually cut the said detectors 5 and 6, the operation of which will be more fully explained hereinafter.

In Fig. 4 we notice a coil I! wrapped around a core l8, said parts being both merely representative of the wire and core, respectively. The purpose of this view is to indicate more definitely that the material used for the core is highly permeable, and is not a permanent magnet. The core l8 in actual practice is made up of several strips of highly permeable material, said core being wrapped with any suitable material, or may he slipped into a hollow fibre sleeve, andaround the core or sleeve is wrapped the wire, which is symbolically shown as IT. The core I 8 is definitely shown to extend beyond the ends of the coil ll. The relation or degree of this protuberance is exceedingly material, in that the range of the detector may be varied by using a shorter or longer core for a coil of given dimensions. While it has not been deemed necessary to set forth any specific dimensions of a coil, it is pointed out that actual tests have shown clearly that the sensitivity of the detector in response to vehicles may be definitely controlled by varying the length of the core inserted within the coil of said detector, and it is pointed out that this feature is exeeedingly advantageous in controlling the range of operation where a single detector is used. To be more specific, assume a detector such as I0 is placed in the highway, as shown in Fig. 2. When a vehicle comes from the right, moving in the direction of the arrow IS, the vehicle, if desiring to move directly toward the left, would pass within a reasonable distance of detector Ill, that is, on the right side of the road. If the road 20 is two lanes wide, that is, one lane for east bound and one lane for west bound traffic, the core of the detector l0 may be shortened so that the ends thereof extend only a slight amount beyond the ends of the coil. However, if the road is a four-lane highway, that is, two lanes for east bound and two lanes for west bound traffic, then it is possible to leave the detector 10 in the same position but increase its range so that the vehicle in the lane adjacent the detector III will be able to operate the signal 3, due to actuation of said detector, and still not have the detector operable by a vehicle in the third or fourth lanes. The sensitivity of the detector It can be increased to any degree, assuming the properties of the material remain the same, merely by increasing the core from any length up to the length which would give the maximum efiiciency for any particular coil.

In Fig. 5 we have an arrangement of the detectors similar to the three detectors shown as 5, 5 and [0 in Fig. 2. It will be noticed that the windings of the three detectors mentioned immediately above are all in series, said coil windings being also in series with the winding of relay 2!, which relay may be any suitable device sensitive enough to cause the armature 22 to be attracted upon actuation of the detector circuit, which may be traced from terminal 23 over a conductor 24, through the winding 25 of detector 5, through the winding 26 of detector 6, over conductor 2? to the winding 28 of detector it, back through conductor 29 to terminal at, then through the relay 2i and returned to terminal 23, said terminals 23 and 30 being shown by legend to be input terminals from the operating or detector circuit. A suitable housing, shown dotted as 3!, schematically represents an enclosure for the electrosensitive element, regardless of the particular form. Terminals 32 and 33 are shown as output terminals for connection to the vehicle con trolled apparatus, which those skilled in the art will understand to be any suitable means which may be connected to the electro-sensitive element to control the apparatus or mechanism, which in turn causes'the operation of the various colored traflic signal lights. We note that the terminal 33 is connected by a conductor 40 through an armature 22, which armature, when energized by the relay 2i, will engage contact 34 to close a circuit through the conductor 35 to the other output terminal 32.

In Fig. 6 we see an electro-sensitive element of the tube type having input terminals similar to those shown in Fig. 5 and labled as 30 and 23, respectively. From the terminal 30 a conductor 35 is connected to a grid of a tube. The element 23 is connected through a battery bias all to a filament of a tube. A relay 38, which functions somewhat similar to relay 2! of Fig. 5, is connected across the plate of the tube to the filament through a battery 39.

planation, as this should be well known to those skilled in the art.

In Fig. 6, a contact set having output terminals, connected thereto, similar to those in Fig. 5, is shown with likecharacters; that is, in Fig. 6 we find a terminal 33 connected to a conductor 40, which engages a contact 36, which will engage the armature 22 when said armature is energized by the relay 38 to close a circuit through conductor 35 back to terminal 32. These terminals 32 and 33 in both Figs. 5 and 6 may be referred to hereinafter as the output terminals.

While it has been set forth previously that the sensitivity of the detector may be controlled by varying the length of the detector core in relation to the amount of extension protruding beyond the coil of wire, it is further set forth that by utilizing two of these detectors having their cores arranged in spaced axial alignment with each other, the sensitivity of the operating circuit may be varied in relation thereto, by changing the distance therebetween.

Referring to Figs. 1 and 3, and particularly to conductor ll in Fig. 3, which is a part of group 9 of Fig. 1, this conductor is shown by legend to be a direct current feeder. A number of arrows pointing downward, shown as' 62, represent lines of force which emanate from the conductor M, said lines of force being shown to move past the detectors 5 and 5. Ordinarily, if one detector was used, such as either 5 or 6, placed in the highway to control the trafilc signal 3 by the passage of a vehicle, such as M, the variations in the flux density of the lines of force 32 caused by power surges might be sufficiently great to cause the signaling circuit connected to terminals 32iit of Fig. 5 to be energized. If this were the case, then each time a power surge was sufiiciently great to cause actuation of the operating circuit shown in Fig. 5, and thereby energize the terminals 32-33, a false signaling would result in the signal lights 3. This is definitely not desirable. Consequently, it is a purpose of this invention to utilize an operating circuit having detectors arranged therein in such a manner that the power surge in one detector will cause a bucking condition will be substantially zero, or negligible, that is, save for minor imperfections in the winding of the coils and the fabrication of the two detectors. Having in mind the variables inherently present in the materials, the result would be that no signal operation would be manifest, due to power surges.

While it is true that power surges from a direct current feeder is herein shown in its reaction upon the detectors, it is nevertheless true that this is purely symbolical and the effect-of any extraneous magnetic field that might be created In Fig. 7 we notice a vehicle, which has a reference numeral M, moving toward the detectors, which may be called 5 and 6, respectively, for the purpose of conformity with the previous description. The vehicle in this particular were able to perfectly split or cause a perfect centre passage as it passed over the de tectors, no resultant or uneven balancing of the current generated would be present to cause the operation of the relay 25 in Fig. 5. However, it is practically impossible to do this, and many tests actually performed with vehicles and other masses of metal with more concentrated magnetism have indicated that it is a practical impossibility. This, then, leads one to believe that while it is theoretically true that this may be the case, actually it is shown that under normal conditions no vehicle is able to achieve the passage over the detectors without causing an unbalancing in the operating circuit. Therefore, we can assume that any vehicle passing within a reasonable distance of the detectors, or within magnetic range of the detectors, will cause the current to be generated unequally in a circuit; that is, more current will be generated in one coil than in the other, resulting in an unbalancing of the circuit and a consequent resultant of circuit actuation and resultant operation of relay 2|.

Figs. 1 and 3 both show the detectors 5 and 6 to have their major axis at right angles to the passage of vehicles on the underpass The purpose of this particular arrangement in the instant showing is two-fold, one reason being so that the flux of the direct current feeder will not cause an unbalancing of the parallel magnetic detectors, and secondly so that the lines of force emanating from the vehicle l5, which is inherently a magnet, will cut the major axis of the magnetic detectors 5 and 6 at right angles so that there will be a minimum influence upon the operating circuit by the passage of the vehicle l5 under the elevated highway I.

Referring to the spacing between the cores ii and II of detectors 5 and 6, it has previously been stated that these parallel detectors may be moved nearer or farther away from each other to eifect sensitivity of the apparatus It is pointed out that the two detectors for the elevated highway act as a single unit and that the unbalanced condition of the operating circuit will cause signal actuation. Since the vehicle it on the elevated highway is in closer relation to the highway than a vehicle underneath, it is pointed out that the spacing between the detectors is not of primary consideration for the vehicles on the elevated highway. However, in regard to the vehicle I5 which moves under the elevated highway, the' proper spacing betwen detectors becomes highly essential.

Assuming that the vehicle i 5 shown at the bottom of Fig. 3 to be substantially directly underneath the magnetic detectors 5 and 6, the particular representative line of force 43 shown definitely on the drawings is schematically representative of the lines of force which may reach the detectors and are shown to be somewhat less arcuate across the upper extremity. It should be clear, then, that if the detectors were spaced a greater distance apart, there would be an actuation of. the operating circuit to cause the lights 3 to be changed, since the effective lines of force would engage one detector before engaging the other, resulting in an oil-balance of the operating circuit. However, by placing the detectors nearer together, such as is shown in Fig. 3, the upper portion of the effective magnetic lines of force, as 43, being somewhat flattened, are parallel with the centre of the detectors 5 and 6. The result is that any change in one detector would be substantially simultaneously effective in the other detector. The result is that before the operating circuit could effect a signal change re-- sulting from action of'one of the detectors, the effect in the other detector would be neutralizing and consequently offset the effect of the first detector.

Hence it is seen that the spacing of the parallel detectors may be such that the range of effect of operation may be definitely controlled. Consequently, it is set forth that by using detectors having their cores placed in spaced axial alignment, it is definitely shown that the effective operating range of automobiles upon detectors may be controlled positively by the spacing between the detectors.

From the foregoing it hasbeen set forth that the arrangement of parts may be such that power lines or extraneous magnetic fields will not affect the operation of the system, and further that the range of the detectors may be controlled by the length of the core in relation to the length of the coil winding and that this effective arrangement may be also controlled by the spacing between two detectors arranged with their cores being placed in spaced axial alignment in relation to each other.

While specific details of the system have been herein shown and described, the invention is not confined thereto, as changes and alterations may be and may become apparent to those skilled in the art without departing from the spirit thereof as defined by the appended claims.

Having thus described the invention, what I claim as new and desire to secure by Letters Patent of the United States, is

1. In a vehicle controlled trafiic signaling apparatus for directional control of traffic in linear motion, a pair of substantially identical detecting elements each comprising a magnetically permeable core and a winding thereupon, condutors serially connecting the coils of said dotecting elements in electrically opposing relationship with respect to voltages induced therein by variations in a substantially uniform magnetic field, and electrically responsive means serially included in the circuit of said conductors.

2. In a vehicle controlled traflic signaling apparatus for directional control of traffic, magnetic detectors comprising an even number of detecting elements responsive to variations in their surrounding magnetic fields, an electro-sensitive element, conductors connecting said detecting elements to said electro-sensitive'element, said electro-sensitive element being responsive only to non-uniform variations in said surrounding fields.

'3. In a traflic signaling system for the detection of units of traffic in substantially linear motion, in combination, a pair of similar cores disposed in substantially parallel juxtaposition, a pair of similar coils, one of said coils being centrally located upon each of said cores an electrosensitive element, and conductors connecting said electro-sensitive element to said coils, whereby said sensitive element will not respond to variations in a substantially uniform magnetic field, in operative proximity to said coils, but said sensitive element being responsive only to variations of operative magnitude in a non-uniform magnetic field.

4. A directional traffic signaling system having a magnetic apparatus for the detection of moving units of traffic, in combination, a pair of normally de-energized detector elements, an electrosensitive element connected to said detector elements and responsive thereto, said detector elements being so disposed that no response of said sensitive element will occur upon passage of a magnetized unit of traflic travelling in such a manner as to produce at every instant a changing differentially connecting said windings to said 76 electro-sensitive element, said electro-sensitive element being responsive only to a substantial difference between the voltages independently generated in the respective detectors.

6. In a traflic signaling system for directional control of vehicular traflic, a magnetically actuable control circuit having a plurality of magnetic detectors, each detector consisting of a coil of wire wrapped around a highly permeable core, said cores extending materially beyond the ends of their respective coils and said cores being placed in spaced axial alignment and being movable in substantially parallel relation to each other to control the efiective range of sensitivity of the magnetically actuable control circuit.

'7. In a vehicle actuable traflic signal for directional control of trafilc, having a magnetically actuable control circuit, a plurality of magnetic devices circuituously connected in said control circuit and located in road-bed of a highway disposed in the approximate path of travel of vehicular trafiic, each detector comprising a coil of Wire and a highly permeable core inserted therein, the longitudinal axis of said cores extending materially beyond either end of each magnetic detector, the degree of extension of the cores beyond the ends of the coil of each detector being dependent upon the desired range of operation in relation to the passage of vehicular trafiic traversing said detectors.

PAUL P. HORNI. 

